Vehicles commonly use intermeshed gears to transmit torque or power in the vehicle, and to operate various vehicle systems or components. The vehicle is provided with an internal combustion engine and a transmission system, each of which may include intermeshing gears. Balance shafts, or counterbalance shafts, may be used with internal combustion engines to cancel unbalanced loads in the engine which are developed from engine operation. A gear train including intermeshed gears is commonly used to transfer rotation to the balance shaft, for example, from a crankshaft.
In conventional engine and counterbalance shaft systems, the intermeshed gears are provided by metal gears; however, these gears may provide limited damping, and the material stiffness properties may result in or be the source of tonal noise (whine), rattle, or other noise vibration and harshness (NVH). The gear-to-gear interaction may result in noise commonly referred to as gear whine. Gear whine is mainly due to the transmission error between meshing teeth of the two gears and may be dependent on several factors including torsional load, gear design, tooth profile, total number of teeth, number of contacting teeth, gear mass, and inertia. Gear whine may be increased in cases with high torsional excitations and may further increase at various orders or harmonics. Metal gears may result in high contact forces at the intermeshing gear teeth due to gear mesh frequencies and lead to whine. Additionally, gear teeth separations caused by gear backlash and the pulsation in the torque or load applied to the gear train may result in a rattling noise. Alternative materials for use in forming the intermeshed gears, such as a plastic, may be limited, based on the high level of torque fluctuations. For example, with a counterbalance shaft on an engine, the torque spikes may be as high as 150 N-m, and alternative materials may have insufficient durability for these applications.